Additional Information

NOTICE: This is the author’s version of a work that was accepted for publication in Lithos. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Lithos, Vol.174, (2013). doi: 10.1016/j.lithos.2012.07.015

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Palaeomagnetic, geochronological and geochemical study of Mesoproterozoic Lakhna Dykes in 1

the Bastar Craton, India: implications for the Mesoproterozoic supercontinent 2

Sergei A. Pisarevskya,b,c,*, Tapas Kumar Biswald, Xuan-Ce Wangb, Bert De Waelee, Richard Ernstf,g, 3

Ulf Söderlundh, Jennifer A. Taita, Kamleshwar Ratred, Yengkhom Kesorjit Singhd, Mads Cleveh 4

a The Grant Institute, University of Edinburgh, King’s Buildings, Edinburgh, UK, EH9 3JW 5

bARC Centre of Excellence for Core to Crust Fluid Systems (CCFS) and The Institute for Geoscience 6

Research (TIGeR), Department of Applied Geology, Curtin University, GPO Box U1987, Perth, WA 7

6845, Australia. E-mail: Sergei.Pisarevskiy@curtin.edu.au 8

cSchool of Earth and Environment, University of Western Australia, 35 Stirling Highway, Crawley, 9

WA 6009, Australia. E-mail:Sergei.Pisarevsky@uwa.edu.au 10

dDepartment of Earth Sciences, Indian Institute of Technology Bombay, Powai, Mumbai, 400076. E-11

mail: tkbiswal@iitb.ac.in 12

eSRK Consulting, 10 Richardson Street, WA6005 West Perth, Australia 13

f Department of Earth Sciences, Carleton University, Ottawa, K1S5B6, Canada 14

gErnst Geosciences,43 Margrave Avenue, Ottawa, K1T3Y2, Canada 15

h Department of Geology, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden 16

17

Abstract 18

Palaeomagnetic analysis of the Lakhna Dykes (Bastar Craton, India) yields a palaeopole at 36.6°N, 19

132.8°E, dp=12.4°, dm=15.9°, and the U-Pb zircon age obtained from one of the rhyolitic dykes is 20

1466.4 ± 2.6 Ma (MSWD=0.21, concordia age based on two analyses with identical Pb/U ages), 21

similar to previously published U-Pb ages. Major and trace element analyses of the Lakhna Dykes 22

show shoshonitic and high-K calc-alkaline affinities consistent with a subduction related 23

characteristics suggesting an active continental margin setting. This is in keeping with the Palaeo- to 24

Mesoproterozoic tectonic environments in the eastern Indian margin. The new 1460 Ma Indian 25

palaeopole was used to test possible palaeopositions of India within the Mesoproterozoic 26

supercontinent Columbia. Of the four palaeomagnetically permissible reconstructions, juxtaposing 27

western India against south-west Baltica is geologically the most reliably constrained and best fitting 28

* Corresponding author; telephone: +61 8 6488 5076; fax: +61 8 6488 1037; e-mail: 29

Sergei.Pisarevsky@uwa.edu.au 30

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model. Our preferred reconstruction implies a long Palaeo- to Mesoproterozoic accretionary orogen 31

stretching from south-eastern Laurentia through south-western Baltica to south-eastern India. Breakup 32

of India and Baltica probably occurred in the Late Mesoproterozoic, but additional constraints are 33

needed. 34

Keywords: paleomagnetism; dykes; supercontinent; Columbia; Proterozoic; India. 35

1. Introduction 36

An increasing number of publications indicates a growing interest in the Mesoproterozoic 37

palaeogeography and to a hypothetic pre-Rodinian supercontinent variously called Nuna, or 38

Columbia, or Hudsonland (e.g., Hoffman, 1997; Condie, 2000; Meert, 2002; Rogers and Santosh, 39

2002, 2009; Pesonen et al., 2003; Zhao et al., 2004; Wingate et al., 2009; Pisarevsky and Bylund, 40

2010; Evans and Mitchell, 2011; Meert, 2012). One of the main reasons for the Columbia hypothesis 41

lies in the widespread evidence for 2.1-1.8 Ga orogens in the majority of Mesoproterozoic continents 42

(e.g., Condie, 2000; Zhao et al., 2004 and references therein) and the suggestion that some or all of 43

these orogens resulted from a supercontinental assembly. Unfortunately, most Columbia 44

reconstructions are highly speculative and sometimes technically incorrect mostly due to a deficit of 45

high quality Late Palaeoproterozoic and Mesoproterozoic palaeomagnetic data. For example, Evans 46

and Pisarevsky (2008) argue that out of 600 published 1600-1200 Ma palaeopoles (Pisarevsky, 2005) 47

for all Precambrian cratons, only eight satisfy all necessary reliability criteria. A few more recently 48

reported palaeomagnetic poles (e.g., Halls et al., 2006; Salminen and Pesonen, 2007; Bispo-Santos et 49

al., 2008, 2012; Lubnina et al., 2010; Pisarevsky and Bylund, 2010) have improved the situation 50

somewhat, but there are still not enough poles to construct an adequate Apparent Polar Wander Path 51

(APWP) for any one craton, let alone the globally disparate cratons. However, the presence of pairs of 52

precisely coeval palaeopoles from the same two cratonic blocks can provide a palaeomagnetic test of 53

the assumption that these two continents drifted together as parts of a larger supercontinent (Buchan, 54

2007; Evans and Pisarevsky, 2008). Luckily there are a few such pairs between 1800 and 1000 Ma: 55

there are reliable palaeopoles from both Laurentia and Baltica at 1780-1740 Ma, 1480-1460 Ma and 56

3

1270-1260 Ma (see Table 2 of Pisarevsky and Bylund, 2010). Additionally there are coeval poles 57

from Siberia and Laurentia at 1480-1460 Ma and even coeval fragments of APWPs for these two 58

continents for ca. 1050-1000 Ma (Pisarevsky et al., 2008; Wingate et al., 2009). These data suggest 59

that these three continents (Laurentia, Baltica and Siberia) could all have been part of a single 60

supercontinent between 1500 and 1270 Ma (Wingate et al., 2009). Published palaeomagnetic data 61

from other continents are not sufficient to establish their relationships with this supercontinent. 62

Ratre et al. (2010) reported a ca. 1450 Ma U-Pb SHRIMP age for the Mesoproterozoic Lakhna dyke 63

swarm located in the eastern part of the Bastar Craton in India (Fig.1). This age is very close to the 64

1480-1460 Ma ages of the abovementioned reliable palaeopoles for Laurentia, Baltica and Siberia. 65

Here we report the results of palaeomagnetic and geochemical studies of the Lakhna Dykes and their 66

implications for the relationship of India and the proposed Mesoproterozoic supercontinent Columbia. 67

2. Geology and sampling 68

Cratonic India comprises the Dharwar, Bastar, Singhbhum, Aravalli and Bundelkhand cratons (e.g. 69

Meert et al., 2010 and references therein; Fig. 1a). The southern cratons (Dharwar, Bastar and 70

Singhbhum) are separated from the northern cratons (Aravalli and Bundelkhand) by the Central India 71

Tectonic Zone (CITZ) or the Satpura Belt. The eastern part of the CITZ was formed during accretion 72

of the Bastar and the Singhbhum cratons to the northern Bundelkhand Craton (Meert et al., 2010 and 73

references therein). The timing of this amalgamation is contentious. Some workers suggest that the 74

main collision occurred at ca. 1500 Ma (Yedekar et al., 1990; Roy and Prasad, 2003), but significant 75

crustal shortening is also reported at ca. 1100 Ma (Roy and Prasad, 2003; Roy et al., 2006). On the 76

other hand, Stein et al. (2004) suggest that the entire Indian cratonic assemblage stabilised during the 77

interval 2.50–2.45 Ga and that all younger displacements were minor. 78

The Archaean Bastar Craton is located in the eastern part of India (Fig.1a). It mostly consists of 79

Palaeoarchaean (3.5-3.6 Ga) TTG basement gneisses and granites (Sarkar et al., 1993, Ghosh, 2004; 80

Rajesh et al., 2009) and relatively undeformed and unmetamorphosed Late Archaean - Early 81

Palaeoproterozoic (~2.5 Ga) granites (Sarkar et al., 1993, Stein et al., 2004), with a number of ca. 82

4

3500 Ma old large gneissic xenoliths. The Bastar Craton is bounded by the Meso- to Neoproterozoic 83

Eastern Ghats Mobile Belt (EGMB) in the south-east along the Terrane Boundary Shear Zone 84

(TBSZ). The 1650-1550 Ma deformational and metamorphic events in the EGMB (Mezger and 85

Cosca, 1999; Rickers et al., 2001; Dobmeier and Raith, 2003), the occurrences of ophiolitic mélange 86

with ages between 1890 and 1330 Ma (Dharma Rao et al., 2011), and the development of foreland 87

basins (Biswal et al., 2003; Chakraborty et al., 2010) all suggest a long-lived Mesoproterozoic active 88

margin setting along the south-eastern edge of India in the late Palaeoproterozoic and 89

Mesoproterozoic (e.g. Meert et al., 2010) . The EGMB also records pervasive high-grade 90

metamorphism and deformation at 985-950 Ma, similar to that identified in the Rayner Complex of 91

Eastern Antarctica (e.g., Harley, 2003; Collins and Pisarevsky, 2005 and references therein; Korhonen 92

et al., 2011), and on the basis of which an earliest Neoproterozoic collision is postulated between 93

proto-India (including the Napier Complex) and the Archaean Ruker Terrane of the southern Prince 94

Charles Mountains, to form the India-Napier-Ruker-Rayner continent (Harley, 2003). 95

Proterozoic dykes are wide spread in the Bastar Craton (e.g. Srivastava, 2006; French et al., 2008; 96

Ernst and Srivastava, 2008; Meert et al., 2010, 2011). Many are undated, but there are at least two 97

mafic igneous events at ~2.3 Ga and at ~1.9 Ga. There are also younger dykes, but many of them are 98

still undated (Meert et al., 2010 and references therein). Dykes which are chemically comparable with 99

the Wai Subgroup of the Deccan flood basalts, have been found near Raipur. Two of them have been 100

recently dated at 63.7 ± 2.7 Ma and 66.6 ± 2.2 Ma (whole rock 40Ar/39Ar, 2σ), which suggests an 101

extension of the Deccan Large Igneous Province far beyond its present exposure (Chalapathi Rao et 102

al., 2011). 103

Several dykes of mafic to felsic composition (Nanda et al., 1998) collectively called the Lakhna dyke 104

swarm are emplaced into the Bastar basement near the EGMB front in the Lakhna area (Fig.1b). Most 105

trend roughly N-S and the swarm includes rhyolite bodies, trachytes and some dolerite dykes with 106

thicknesses of 10-30 m (Fig.1b). Several smaller dolerite dykes of an EW to NW-SE trend cut the N-S 107

dykes in several places. Two coarse-grained NNW-SSE trending mafic dykes are found in the western 108

part of the studied area (Fig.1b). One coarse-grained deformed gabbro intrusion within the TBSZ is 109

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provisionally included into the Lakhna swarm. Ratre et al. (2010) reported zircon U-Pb SHRIMP ages 110

for three Lakhna Dykes Tr (TKB-7), D5 (TKB-6) and G1 (TKB-8): 1442 ± 30 Ma, 1450 ± 22 Ma and 111

1453 ± 19 Ma respectively (Fig.1b). In 2009 we collected 131 oriented cores for palaeomagnetic 112

analyses from dykes D1-D10, Tr1 and G1 (Fig. 1b). Parts of these cores were used for 113

geochronological and geochemical studies. Dykes are exposed either on the hill slopes, or in small 114

pits. Unfortunately we could not find exposed cross-cuts or well preserved contacts with country 115

rocks, so it was not possible to carry out any baked contact tests. Additionally, 22 samples were 116

collected specifically for geochemical studies. All sampling sites are shown in Fig. 1b. 117

3. Analytical methods 118

3.1 Palaeomagnetism 119

Remanence behaviour was determined by detailed stepwise alternating field (AF) demagnetisation (≤ 120

20 steps, up to 100 mT), using an AGICO LDA-3A tumbling demagnetiser. Thermal demagnetisation 121

(≤ 20 steps, to 600°C) was also applied using a Magnetic Measurements MMTD1 furnace and the 2G 122

cryogenic magnetometer in the University of Edinburgh. Magnetic mineralogy was investigated from 123

demagnetisation characteristics and, in selected samples, from detailed variation of susceptibility 124

versus temperature (20 to 700°C) obtained using the Bartington meter in conjunction with an 125

automated Bartington furnace. Parts of the collection were studied in the palaeomagnetic laboratories 126

of Oxford University (UK), Utrecht University (Netherlands), University of Western Australia, 127

University of Bergen (Norway) and Luleå University of Technology (Sweden). Magnetisation vectors 128

were identified using Principal Component Analysis (Kirschvink 1980). 129

3.2 Geochronology 130

Approximately 100 grams of sample from the Lakhna dyke D5 was processed for U-Pb 131

geochronology at the Department of Geology at Lund University, Sweden, using standard procedures. 132

The ca. <200 µm fraction of crushed material was carefully mixed with water before being loaded in 133

portions (ca. 50 g per portion) on a Wilfley table (for details see Söderlund and Johansson, 2002). U-134

Pb TIMS analyses were performed at the Laboratory of Isotope Geology (LIG) and at the Natural 135

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History Museum of Stockholm. Further details of mass spectrometry analysis, data reduction and 136

regression are given by Nilsson et al. (this volume). 137

3.3 Geochemistry 138

After petrographic examination, the least-altered samples were selected for whole-rock geochemical 139

analyses. The rocks were crushed into small fragments (< 0.5 cm in diameter) before being further 140

cleaned and powdered in a tungsten mill. Quartz was crushed and the mill cleaned using compressed 141

air between each sample to avoid contamination. A small amount of ca. 30 grams was taken from 142

each sample and transferred to plastic containers and sent to the Acme Analytical Laboratories Ltd 143

(Canada) for major and trace element analyses (Acme codes 4A-4B and 1DX). Total abundances of 144

the major oxides and several minor elements were determined on a 0.2 g sample analysed by ICP-145

emission spectrometry following a Lithium metaborate/tetraborate fusion and dilute nitric digestion, 146

while rare earth and refractory elements were determined by ICP mass spectrometry following a 147

Lithium metaborate / tetraborate fusion and nitric acid digestion of a 0.2 g sample aliquot. In 148

addition, a separate 0.5 g split was digested in Aqua Regia and analysed by ICP Mass Spectrometry 149

for Mo, Cu, Pb, Zn, Ni, As, Cd, Sb and Bi. Based on repeated analyses (n=21) of an in-house 150

reference sample prepared by GEUS (Geological Survey of Denmark and Greenland) the analytical 1 151

sigma uncertainties are between ±0.4% and ±1.1% for SiO2, Al2O3, Fe2O3, MgO, Na2O, and Ti2O and 152

between ±2.4 and ±4.8% for K2O, TiO2, CaO, MnO and P2O5 (Kokfelt, pers. comm., 2012). Results 153

are presented in Table 3. 154

The geochemical analyses of 22 additional dyke samples representative of this swarm, were carried 155

out using ICP-AES analysis (Jobin-Vyon Horiba, model: Ultima-2), X-ray fluorescence spectrometer 156

(XRF) and ICP-emission spectrometry at the Department of Earth Sciences, Indian Institute of 157

Technology, Bombay. 0.25 grams of powdered sample were fused with 0.75-gram lithium 158

metaborate and 0.25-gram lithium tetraborate in platinum crucibles at a temperature of 1050°C in a 159

muffle furnace. After cooling, the crucible was immersed in 80 ml of 1M HCl contained in a 150 ml 160

glass beaker and then magnetically stirred until the fusion bead had dissolved completely. Then the 161

sample volume was made up to 100 ml in a standard volumetric flask. The same procedure was 162

7

adopted to make standard solutions and blank sample. The standards used for the analyses include 163

JSy-1 (syenite), JGb-2 (Basalt), JR- 3 (Rhyolite), JG-2 (Rhyolite), JG-1a (Granodiorite) (GSJ 164

Reference standards, 1998). Major, trace and LOI elements were estimated from the above solution by 165

ICP-emission spectrometry. Results are presented in Table 4. The 2σ uncertainties are between 166

0.004% and 0.3% for SiO2, Al2O3, Fe2O3, MgO, CaO, Na2O and K2O and between 0.001% and 0.1% 167

for TiO2, MnO and P2O5. Repeated runs give <10% RSD (relative standard deviation) for most trace 168

elements analysed. Results of standard analyses for both laboratories are provided in Appendix C. 169

4. Transmitted and reflected light microscopy 170

The studied rhyolites are pink coloured, fine to medium grained rocks consisting of phenocrysts of 171

rounded to amoeboid quartz and euhedral to subhedral alkali feldspar grains (Fig. 2a). The matrix is 172

fine to medium grained and exhibits extensive graphic intergrowth. Magnetite, zircon and green 173

biotite occur as accessory minerals. 174

The trachytes are fine to medium grained, light greenish to very dark coloured rocks with aphanitic 175

and mesocratic textures (Fig. 2b). Well-developed flow layers, defined by needle-shaped alkali 176

feldspar grains, are present in the rock. Glomeroporphyritic textures are developed due to segregation 177

of multiple feldspar phenocrysts, with flow layers swerving around these aggregates. 178

The dolerites are dark to greenish coloured medium grained rocks, consisting of plagioclase, augite, 179

opaques (magnetite) and amygdales (Fig. 2c). An intergranular texture is prominently developed, with 180

augite crystals packed within triangular arrays of plagioclase crystals. An intersertal texture is also 181

present where glass occurs inside the arrays. 182

The alkali gabbros are coarse grained, dark coloured rocks and contain crude mylonitic foliations 183

close to the TBSZ. In the less deformed units, a cumulus texture between plagioclase, orthoclase, 184

hornblende and relict augites has been observed (Fig. 2d). Ophitic and subophitic textures are 185

prominent with randomly oriented euhedral laths of plagioclase embedded fully or partly in larger 186

pyroxene (or hornblende after augite) crystals. In more deformed portions, a low grade metamorphism 187

has transformed the augites to hornblende. 188

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A reflected microsopy study of the dykes reveals that the opaques are dominantly magnetite which are 189

martitised to varying extent. Magnetite grains in dolerite and trachyte cores are coarse, euhedral to 190

subhedral with polygonal crystalline forms. These have been variously altered to martite along cubic, 191

octahedral planes, fractures and grain boundaries (Fig.2e - for dolerite dyke D2, Fig.2f - for trachyte 192

dyke D10). Figure 2g (rhyolite dyke MA1) shows a photomicrograph of a rhyolite sample where the 193

magnetite occurs as very fine grained crystals disseminated throughout the rock. With larger 194

magnification (Fig. 2h) magnetite grains in the rhyolite are found to occur inside quartz and feldspar 195

phenocrysts. The form and mode of occurrence of all these grains indicate the primary nature of 196

magnetite in all studied rock types. 197

5. Palaeomagnetism 198

Natural remanent magnetisation (NRM) intensities of samples range from 0.1 to 8.7 A/m for the 199

dolerites, from 1 to 90 mA/m for the trachyte dykes, and from 1 to 200 mA/m for the rhyolite dykes. 200

Magnetic susceptibilities are within 0.5-30x10-3, 1.5-3.9x10-4 and 4.0-94.0x10-5 SI units 201

correspondingly. Twenty samples proved to be very strongly magnetised with chaotic palaeomagnetic 202

directions and are interpreted as having been subjected to lightning strikes. These samples have been 203

excluded from further discussion. 204

Thermomagnetic curves (low-field magnetic susceptibility versus temperature) for dolerite samples 205

show Hopkinson peaks close to 550°C (Fig. 3), confirming the presence of fine-grained single-206

domain titanium-poor titanomagnetite. 207

In the great majority of samples both thermal and AF demagnetisation isolated a single stable bipolar 208

remanence component carried by low-titanium titanomagnetite with unblocking temperatures between 209

500°C and 580°C. After removal of low-stability, randomly oriented overprints, ten dykes exhibit 210

either a medium to steep downward (D1-D6, D10, Tr1), or upward (D7, D8) direction of remanence 211

(Fig. 4, 5; Table 1). There were no cases of mixed magnetic polarity within one dyke which supports a 212

primary bipolar origin of the remanence. The magnetic remanence of samples from the dolerite dyke 213

9

D9 and from the alkali gabbro G1 is chaotic and the results from these dykes were excluded from the 214

interpretations. 215

In the absence of contact tests we used the following lines of evidence for the primary origin of the 216

stable remanence. First, the study of polished sections and thermomagnetic analysis (Figs. 2 and 3) 217

indicates the presence of small grains of magnetite including single-domain (SD) grains. Single 218

domain magnetite is a highly stable palaeomagnetic recorder, and must be heated close to 580°C to 219

reset its remanence (e.g. Pullaiah et al. 1975; Walton 1980). As the dykes have not been 220

metamorphosed, such reheating is considered unlikely. Second, the presence of polarity reversals 221

between, but not within, intrusions is supportive of a primary remanence. Third, the mean high-222

temperature remanence direction (both polarities) is different from all younger reliable Indian data 223

(see discussion and McElhinny et al., 2003). 224

The remanence directions (Table 1) show no correlation with dyke trends nor with rock types, which 225

suggests a relatively short interval of dyke emplacement, which is also supported by the similar ages 226

of the dated dykes. On the other hand, the presence of two polarities indicates that at least one 227

geomagnetic reversal occurred during this interval, which gives an adequate time for averaging out 228

the geomagnetic secular variations. Remanence directions of two dolerite dykes (D4 and D8, the latter 229

– after polarity inversion) fall a bit outside the main group of directions (Table 1), so their exclusion 230

improves the statistics (Table 1, Fig. 5). However, Table 1 and Fig. 5 presents both the mean direction 231

for ten dykes and for eight dykes. The former has been used for the palaeogeographic reconstructions 232

in section 7. 233

6. Geochronology 234

A fraction of prismatic (length:width is 1.5-2), slightly pinkish, euhedral zircon grains (and 235

fragments) were separated from the rhyolitic Lakhna dyke D5 (star in Fig. 1b). No overgrowths or 236

xenocrysts (cores) were observed from back-scattered electron imaging confirming the zircons 237

represent a homogenous (single) population with typical magmatic characteristics (Fig. 6). The ca. 50 238

optically best grains were subjected to physical air abrasion (Krogh, 1982). From these, six grains 239

10

were selected and combined into two fractions. Both fractions yield results which are >95 concordant 240

and provide a Concordia age of 1466.4 ± 2.6 Ma (MSWD = 0.21), interpreted to date the 241

emplacement of the dyke. The Concordia diagram is shown in Fig. 7 with isotopic data in Table 2. 242

The age is within the precision limits of a previously obtained zircon U-Pb date of 1450 ± 22 Ma from 243

the same dyke (Ratre et al., 2010). 244

7. Geochemistry 245

7.1 Major and trace elements 246

The major and trace element data are presented in Tables 3 and 4. The studied samples fall into the 247

alkalic and sub-alkalic fields (Fig. 8a, on a volatile-free basis). For the mafic samples (SiO2 <53 248

wt.%), total alkalis decrease with increasing SiO2, suggesting source heterogeneity. Two silica over-249

saturated (SiO2 = 51-54 wt.%) mafic rocks (MM4 and MM6 from the alkaline gabbro G1, Fig. 1b) 250

have extremely high total alkalis (13-14 wt.%), plotting in the phonolite field (Fig. 8a). Based on the 251

chemical composition of representative fresh samples (Table 3, 4), the studied rocks vary from 252

basanites/basalts/basaltic andesite to trachytes/rhyolites, according to the IUGS nomenclature (Le Bas 253

et al., 1986; Fig. 8a). The samples are characterised by high K2O at given silica contents and define 254

two trends: an alkali series trend and a sub-alkalic series trend (Fig. 8b). More than half of the 255

samples (19 of 34) fall within the shoshonite field of Peccerillo and Taylor (1976, Fig. 8b). 256

The studied dykes have a wide range of major element abundances (Table 3). The mafic samples, 257

with SiO2 = 45 wt.% to 55 wt.%, show a decrease in TiO2, FeOTotal, MgO, and CaO and increase in 258

Al2O3 with increasing SiO2 (see the Harker plots in Appendix A). The andesitic to rhyolitic samples 259

with SiO2 > 55 wt.% have relatively constant TiO2 and CaO abundances and display a slow decrease 260

in FeO* and Al2O3 with increasing SiO2. Na2O variations with SiO2 clearly indicate two trends within 261

the dykes. Similarly two trends are visible in the magnesium variations. 262

The alkalic and sub-alkalic mafic dykes display different trace element patterns (Figs. 9-10). The 263

alkalic mafic dykes (Group 1, see also Tables 3 and 4) display enrichment in light rare earth elements 264

(LREE) with (La/Sm)N (chondrite normalised values) = 2.7 to 4.9 and (La/Yb)N = 14 to 32, whereas 265

11

the sub-alkalic mafic dykes (Group 2, see also Tables 3, 4) have LREE-enriched REE patterns with 266

(La/Sm)N= 1.3 to 2.2 and (La/Yb)N = 1.7 to 3.9 (Fig. 9). Samples MM4, MM8 (alkaline gabbro) from 267

Group 1 are characterised by extremely enriched light rare earth elements (LREE) with (La/Sm)N= 3.9 268

to 4.9 and (La/Yb)N = 22 to 32 (Fig. 9). Group 1 displays high enrichment in large ion lithophile 269

elements (LILE) and light rare earth elements (LREE) (Fig. 10). Group 2 exhibits low LILE and 270

LREE except for Th, with relatively flat primitive mantle normalised trace element patterns. The 271

andesitic dykes mainly plot with the alkalic series (Group 1) with uniform REE patterns (Fig. 9) with 272

(La/Sm)N = 2.7 to 3.0 and (La/Yb)N = 11 to 14, and flat primitive mantle normalised trace element 273

patterns (Fig. 10). The felsic samples (dacite to rhyolite) exhibit uniform trace element compositions 274

with significant depletion of Eu (Fig. 9). 275

7.2 Interpretation 276

7.2.1 Effects of alteration on the geochemical systems 277

All samples used in this study exhibit low LOI values (0-3.5 wt.%, mostly <2.5 wt.%), suggesting that 278

the effects of alteration on chemical composition are insignificant. Zirconium, an immobile element 279

during low-degree metamorphism and alteration, can be used as an alteration-independent index of 280

geochemical variations. Bivariate plots of Zr against selected trace elements can thus be used to 281

evaluate the element mobilities during alteration (e.g., Polat and Hofmann, 2003; Wang et al., 2008, 282

2010). The high field strength elements (HFSE, such as Nb, Ta, Ti, Zr, Hf), rare earth elements 283

(REE), Y, and Th are correlated with Zr, indicating that these elements are essentially immobile 284

during alteration. A weaker correlation between abundances of Na and K versus Zr (r = 0.46 for K 285

and 0.56 for Na), imply only a slight effect of deuteric or hydrothermal alteration on these two 286

elements (Appendix B). Rb, alkaline earth (such as Ca, Sr, and Ba), Pb and Mn elements are all 287

scattered, implying varying degrees of mobility. 288

7.2.2 Crystal fractionation and crustal contamination 289

The low abundances of MgO, Cr and Ni in the mafic samples in this study indicate significant prior 290

olivine crystal fractionation. The decrease of TiO2, CaO, FeOTotal, and MgO with increasing SiO2, and 291

12

the increase of Al2O3 with increasing SiO2 suggest that mafic samples underwent variable crystal 292

fractionation of olivine + clinopyroxene ± Ti-Fe oxides (Appendix A). The kink on trends of TiO2, 293

Al2O3, CaO and FeOTotal versus SiO2 (SiO2 = 55-60 wt. %) reflects the appearance of plagioclase on 294

the liquidus (Appendix A). This is confirmed by significant depletion of Eu in felsic samples (Fig. 9). 295

The diagrams of Na2O and K2O versus SiO2 (Fig. 8) indicate two distinctive parental magmas: one 296

with high Na2O (about 8 wt.%) and K2O (about 3 wt.%) content and another with low Na2O (about 3 297

wt.%) and K2O (< 1 wt.%) content. This is consistent with the two distinctive types of trace element 298

compositions. 299

The effect of crustal assimilation can be evaluated by comparing the concentration of major elements 300

SiO2 and MgO, with trace element ratios of Nb/La, Th/La and La/Yb. The lack of correlations 301

between SiO2 (MgO) and Nb/La, Th/La, and La/Yb (Fig. 11) implies that crustal contamination 302

played an insignificant role in the generation of these dykes. 303

7.2.3 Magma source characteristics and petrogenesis 304

The two types of basaltic samples display distinctive trace element and alkaline signatures, implying 305

derivation from different source regions. Basaltic samples of Group 1 are not normal products of 306

melting of mantle peridotite as indicated by their extremely high trace element concentrations. For 307

instance, the typical Group 1 samples MA4, MM4 and MM8 have about 10 times of an average of 308

typical alkaline OIB (Fig. 9). We interpret this distinct geochemical signature to suggest that they 309

derived from a hydrous mantle source, reflecting the contribution of melt released from the subducted 310

slab and/or melts (Polat et al., 2011, 2012). 311

Basalts of Group 2 display a large range of trace element compositions without significant depletion 312

of Nb, Zr, Hf and Ti, broadly similar to typical alkaline OIB. Compared to Group 1 basalts, they are 313

characterised by relatively low SiO2 (50-44 wt.%) and high FeOTotal (14-12 wt.%) and TiO2 (1.6-3.6 314

wt.%) contents. These features suggest that these basaltic samples were likely directly derived from 315

asthenospheric mantle. 316

13

Analysed andesitic dykes mainly belong to alkalic series with an OIB-like trace element pattern, 317

similar to mafic samples of Group 2. Thus, the Group 2 basalts may be the parental magma of these 318

andesitic samples. The trachytic to rhyolitic samples exhibit relatively uniform trace element patterns. 319

These felsic dykes are characterised by enrichment of potassium and plot within the fields ranging 320

from high-K calc-alkaline to shoshonitic series. Shoshonitic series generally have restricted spatial 321

and temporal distribution, and the ultimate origin of the magmatism has commonly been related to 322

thermal events in the mantle, usually related to collision events, such as slab break-off (e.g., 323

Aldanmaz et al., 2000; Kay and Mahlburg Kay, 1993; Morrison, 1980; Pe-Piper et al., 2009). The 324

generation of shoshonites is generally thought to be related to incorporation of subducted sediments in 325

the active continental margin, but also can be produced within an intraplate tectonic setting by partial 326

melting of sub-continental lithospheric mantle (SCLM) which has been metasomatically enriched in 327

an earlier subduction event (Scarrow et al., 2008). 328

8. Discussion 329

8.1 Tectonic setting of the Lakhna Dyke Swarm 330

Based on major element geochemistry only, Ratre et al. (2010) proposed that the Lakhna dyke swarm 331

may have been generated within an extensional tectonic setting, as earlier suggested by Nanda et al. 332

(1998). However, as shown in Fig. 1b, the dyke swarm can be divided into sub-groups according to 333

their orientation. The two sub-groups are nearly perpendicular, but have the same ages, which seems 334

inconsistent with a typical rift setting. 335

The new geochemical data (major and trace element) clearly indicate shoshonitic and high-K calc-336

alkaline affinities, consistent with a subduction related setting, with the former representing late stage 337

arc-magma (Scarrow et al., 2008). The coexistence of high-K calc-alkaline with shoshonitic series is 338

favoured here to reflect an active continental margin setting in accord with other studies (e.g., Dharma 339

Rao et al., 2011, 2012; Santosh, 2012). 340

8.2 Palaeomagneticaly permissive positions of India in Columbia. 341

14

The available palaeomagnetic data permit a fixed configuration between Laurentia, Baltica and 342

Siberia from ~1500 Ma to ~1270 Ma (Salminen and Pesonen, 2007; Wingate et al., 2009; Pisarevsky 343

and Bylund, 2010) suggesting that they formed a part of Columbia. Our new 1465 ± 3 Ma Indian 344

palaeopole is coeval to the highly reliable poles from these continents (Table 5; Fig. 12), providing an 345

opportunity to test possible positions of India in Columbia. Of course, it must be borne in mind that: 346

(i) India could be unconnected to Columbia; (ii) India could be juxtaposed not to Laurentia, Baltica or 347

Siberia, but to some other part of Columbia, whose position is not yet constrained. With these 348

limitations our new palaeopole allows four reconstructions with India juxtaposed against Laurentia, 349

Baltica, or Siberia (Fig. 12a-d) at 1460 Ma. 350

Using other precisely dated Mesoproterozoic Indian palaeopoles (Table 5, entries 29-32) and coeval 351

poles from Laurentia, Baltica and Siberia, we shall test the viability of these reconstructions at ca. 352

1190, 1120 and 1080 Ma. Euler rotation parameters for Laurentia, Baltica and Siberia are listed in 353

Table 6 and the rotation parameters for India are given in figure captions. 354

The 1192 ± 10 Ma Harohalli pole (Table 5, entry 29) is coeval to two Laurentian poles from the 1184 355

± 5 Ma intrusions in Greenland (Table 5, entries 8 and 9). Figure 13a demonstrates that the 1460 Ma 356

reconstruction of India juxtaposed to SE Laurentia (Fig. 12a) could not have persisted until 1190 Ma. 357

The corresponding Euler rotation parameters applied to the Indian pole move it to low latitudes ~60° 358

away from the geographic pole approximated by Laurentian palaeopoles, implying India-Laurentia 359

separation before ca. 1190 Ma. The ca. 1080 Ma Indian palaeopoles are also discordant with coeval 360

Laurentian poles in the tested reconstruction (Table 5, Fig. 13a). 361

Geological data are also not supportive to the India – SE Laurentia fit. The SE edge of Laurentia has 362

been a long-lived 1.8 – 1.0 Ga convergent orogen (e.g., Karlstrom et al., 2001). The eastern edge of 363

India should also be considered as long-lived active margin during roughly the same time interval (see 364

Section 8.1). Figure 12a shows that the India – SE Laurentia reconstruction requires juxtaposition of 365

two active continental margins with opposite directions of tectonic transport thus discounting this 366

reconstruction as a viable option. 367

15

As shown in Fig.12b and 13b, palaeomagnetic data permit positioning of India against the western 368

margin of Laurentia (present-day co-ordinates) from 1460 Ma until 1190 Ma, given that the circles of 369

95% confidence for the Laurentian and Indian poles overlap. However, if such a connection existed, 370

palaeomagnetic data dictate that it must have been broken before 1080 Ma (Fig. 13b). 371

The western margin of Laurentia contains a rift – passive margin succession initiated at c. 750 Ma 372

(e.g., Moores, 1991; Ross et al., 1995; Dehler et al., 2010). It remains a matter of debate as to which 373

continent separated from this Laurentian margin, possible candidates including: Australia (e.g., 374

Moores, 1991; Dalziel, 1991; Hoffman, 1991; Brookfield, 1993; Karlstrom et al., 1999; Burrett and 375

Berry, 2000; Wingate et al., 2002), South China (Li et al., 1995), Siberia (Sears and Price, 2000), 376

West Africa, or Rio de La Plata (Evans, 2009). Late Mesoproterozoic palaeomagnetic data rule out an 377

Australia-Laurentia connection at ~1.2 Ga (Pisarevsky et al., 2003). A Siberia-W. Laurentia fit also 378

failed palaeomagnetic tests and has problems with geological mismatches (Pisarevsky and Natapov, 379

2003; Pisarevsky et al., 2008). A lack of reliable Mesoproterozoic palaeomagnetic data prevents 380

similar tests for South China, West Africa and Rio de La Plata. 381

Major geological features (Fig. 12b) permit connections between the Archaean Dharwar Craton and 382

the displaced fragment of the Slave Craton, and also between Indian Aravalli and Bundelkhand 383

cratons, and Hearne, Wyoming and Medicine Hat blocks of Laurentia. The earliest deformations in 384

CITZ (2100-1900 Ma; Mohanty, 2010) are similar in age to those in the Taltson Belt of Laurentia 385

(Hoffman, 1989). Both orogens have the same trend in this reconstruction. This reconstruction also 386

juxtaposes the Lakhna magmatism with the widespread coeval magmatism in adjacent western 387

Laurentia (e.g., Anderson and Davis, 1995; Ernst and Buchan, 2001; Ernst et al., 2008; Harlan et al., 388

2008). However, in our preferred interpretation of the geochemistry the Lakhna Dykes are associated 389

with subduction processes, which would contradict this comparison. The timing of sedimentation in 390

the Mesoproterozoic Belt Basin (Fig. 12b) in Laurentia (e.g., Luepke and Lyons, 2001) is overlapping 391

with that in Vindhyan basins of India (Malone et al., 2008; Meert et al., 2010). According to 392

palaeomagnetic data (Figs. 12b, 13b) the separation of India from Laurentia should occur between 393

1190 and 1080 Ma. However, there is strong evidence that continental breakup along the western 394

16

Laurentian margin occurred not earlier than ca. 750 Ma (e.g., Moores, 1991; Ross et al., 1995; Dehler 395

et al., 2010). 396

There are no reliable Siberian palaeopoles between ca. 1460-1050 Ma (Table 5). However, there is 397

good evidence that Laurentia and Siberia were in a fixed position with respect to each other between 398

ca. 1470 -1000 Ma (Wingate et al., 2009). Consequently the 1460-1050 Ma Laurentian poles can be 399

used for palaeomagnetic testing of the western India – SW Siberia reconstruction (Fig. 12c) at 1190 400

Ma and 1080 Ma (Fig. 13c). As in the previous case, the proposed India-Siberia reconstruction is 401

palaeomagnetically permissive at 1190 Ma, but not later. Geological data do not support juxtaposition 402

of India and SW Siberia in the Mesoproterozoic (Fig. 12c). First, even though the Archaean Dharwar 403

Craton and the Archaean Tungus Terrane are close in this reconstruction, they are separated by the ca. 404

1.9 Ga Angara orogenic belt (Rosen et al., 1994; Condie and Rosen, 1994), which contradicts the idea 405

of their common origin. Second, Gladkochub et al. (2006a, b) demonstrated that the continental 406

breakup and sedimentation on the SW Siberian passive margin did not commence until after ca. 750 407

Ma. We conclude that the proposed India-Siberia reconstruction is not viable. 408

Fig. 12d shows the fourth reconstruction with the Dharwar Craton of India juxtaposed to Sarmatia 409

(Baltica). The VGP from the 1122 ± 7 Ma Salla dyke of Baltica (Table 5) is, within the error limits, 410

coeval to the 1113 ± 7 Ma Mahoba palaeopole from India (Pradhan et al., 2012). Circles of 411

confidence of these poles overlap (Fig. 13d), so it is possible that at that time India and Baltica were 412

still together. Palaeopoles for Baltica and India at ca. 1080 Ma demonstrate that the two continents 413

must have separated by this time. Hence the Baltica-India reconstruction shown in Fig. 12d could be 414

true from 1460 Ma until 1120 Ma. In the tested reconstruction the Archaean Dharwar and Sarmatia 415

cratons are located next to each other (Fig. 12d) suggesting that they formed part of a single proto-416

craton. Sarmatia consists of several terranes which welded together in the latest Archaean – earliest 417

Palaeoproterozoic (Bogdanova et al., 1996). The Dharwar Craton has a somewhat similar history 418

whereby the eastern and western parts were welded together at ca 2515 Ma (Meert et al., 2010). Late 419

Archaean and Palaeoproterozoic banded iron formations (BIFs) are widespread in Sarmatia and 420

Dharwar (Fig. 12d). Sarmatia is bounded by the 2.10-2.02 Ga Lipetsk-Losev/East Voronezh Belt 421

17

(Fig. 12d; Schipansky et al., 2007; Bogdanova et al., 2008). Deformation and UHT metamorphism of 422

similar age (2040 ± 17 Ma) has been reported from CITZ (Mohanty, 2010, 2012). Trends and 423

positions of these two orogens also suggest their possible relationship (Fig. 12d). Many 424

Mesoproterozoic (ca. 1.4-1.0 Ga) kimberlites and lamproites are reported both from Dharwar and 425

Sarmatia (e.g., Chalapathi Rao et al., 2004; Kumar et al., 2007; Bogatikov et al., 2007), however, 426

many of these are not precisely dated, precluding any direct correlations. 427

An India-Baltica reconstruction (Fig. 12d) aligns the eastern margin of India with the southern 428

segment of the SW margin of Baltica. The Proterozoic tectonic history of Baltica is characterised by 429

the prolonged accretion from the present west (Fig. 12b; Gorbatschev and Bogdanova, 1993; 430

Bogdanova et al., 2001; Åhäll and Connelly, 2008; Bingen et al, 2008; Bogdanova et al., 2008). The 431

1.85-1.33 Ga ophiolitic melange in the EGMB of India (Fig. 12d; Dharma Rao et al., 2011) suggest a 432

long-lived active margin environment along the eastern Indian margin. This is supported by the 433

development of foreland basins (Biswal et al., 2003; Chakraborty et al., 2010) and by geochemical 434

data (see above). It was previously suggested that the SW Palaeo- to Mesoproterozoic active margin 435

of Baltica is a continuation of the accretionary margin of Laurentia (e.g., Karlstrom et al., 2001; 436

Pisarevsky and Bylund, 2010). If our hypothesis is correct, this implies a giant nearly linear long-lived 437

Palaeo- to Mesoproterozoic ‘Laurentia-Baltica-India’ accretionary orogen comparable in scale with 438

the present eastern Pacific active margin. 439

Palaeomagnetic data suggest that India broke up from Baltica between ca. 1120 and 1080 Ma. 440

However, there is no evidence of Mesoproterozoic rifting in the western Dharwar Craton. Such 441

evidence could be concealed in the recently rifted Seychelles Block and/or Antongil Terrane of 442

Madagascar. However, these blocks were strongly tectonically overprinted in Neoproterozoic and 443

Cambrian times (Tucker et al., 2001; Schofield et al., 2010). Similarly, the SW margin of Sarmatia is 444

mostly covered and probably overprinted by the Cadomian orogeny. Bogdanova et al. (1996) 445

suggested that the 1.3-1.1 Ga Volyn-Orsha Aulacogen (Fig. 12d) could represent the failed-arm of a 446

triple junction, which implies that the successful rifting could occur along the Teisseyre-Tornquist 447

line, which may also represent the rifting between Baltica and India. Poprawa and Pacześna (2002) 448

18

suggested that this rifting could have occurred during the Mesoproterozoic. The 1.3-1.1 Ga mafic sills 449

in the western part of the Volyn-Orsha Aulocogen (Bogdanova et al., 2008) indirectly provide some 450

constraints on the timing of rifting between Baltica and India. 451

Altogether among other discussed possibilities this reconstruction with India juxtaposed to Baltica is 452

considered to be the most robust model. 453

9. Conclusions 454

1. A new U-Pb age of 1465 ± 3 Ma from the rhyolitic D5 Lakhna Dyke in the Bastar Craton of India 455

is similar to previously published U-Pb zircon dates of this and two other dykes of the Lakhna Dyke 456

Swarm. 457

2. Geochemical data from the Lakhna Dykes indicate shoshonitic and high-K calc-alkaline affinities 458

suggesting that they are related to subduction in an active continental margin setting. 459

3. A palaeomagnetic study of the Lakhna dykes has provided a new robust 1460 Ma palaeopole for 460

India, which is coeval to reliable palaeopoles from Laurentia, Baltica and Siberia. 461

4. Indian geology and Precambrian geological data from Laurentia, Baltica and Siberia suggest that, 462

among four palaeomagnetically permissive positions of India, the reconstruction of western India 463

attached to south-west Baltica (Sarmatia) is geologically and palaeomagnetically the most permissible 464

model. The reconstruction implies a long-lived nearly linear Palaeo- to Mesoproterozoic mega-465

accretionary orogen along south-eastern Laurentia, south-western Baltica and eastern India. This 466

orogen was comparable in terms of scale with the present Cordillieran-Andean orogen in America. 467

Acknowledgements 468

Palaeogeographic reconstructions are made with free GPLATES software (http://www.gplates.org/). 469

This is contribution xx from the ARC Centre of Excellence for Core to Crust Fluid Systems, and 470

TIGeR publication #xx and also publication #19 of the LIPs-Supercontinent Reconstruction Project 471

19

(http://www.supercontinent.org). SP and JT gratefully acknowledge funding from the Marie Curie 472

FP6 Excellence Grant scheme. 473

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paleogeography. Precambrian Research 170, 256-266. 1010

Yedekar, D.B., Jain, S.C., Nair, K.K.K., Dutta, K.K., 1990. The central Indian collision suture, 1011

Precambrian of Central India. Geological Society of India Special Publication 57, 9-25. 1012

Zartman, R.E., Nicholson, S.W., Cannon, W.F., Morey, G.B., 1997. U-Th-Pb zircon ages of some 1013

Keweenawan Supergroup rocks from the south shore of Lake Superior. Canadian Journal of Earth 1014

Sciences 34, 549-567. 1015

Zhao, G., Sun, M., Wilde, S.A., Li, S., 2004 A Paleo-Mesoproterozoic supercontinent: assembly, 1016

growth and breakup. Earth-Science Reviews 67, 91–123. 1017

1018

Figure captions 1019

Fig. 1. (a) Location and geological province map of India (geology based on, Commission for the 1020

Geological Map of the World, 2000); (b) Geological map of the Lakhna area and sampling sites. The 1021

cross-section is approximately along 20°40' 30'' N. 1022

Fig. 2. Photomicrographs in transmitted (a-d) and reflected (e-h) light: (a) rhyolite showing quartz (Q) 1023

and feldsdpar phenocrysts (Or) in a fine to medium grained quartzofeldspathic groundmass; (b) 1024

trachyte with single or multiple feldspars phenocrysts (Or-Orthoclase, Plg- Plagioclase); (c) dolerite 1025

30

showing augite (Px) (colored mineral) and plagioclase (Plg) (white and grey shade) crystals with 1026

irregular grain margin; (d) alkali gabbro showing intergrowth between alkali (Or) and plagioclase 1027

feldspars (Plg); magnetite (Mag) with martite (Mar) minerals of the different dyke sections (e) 1028

dolerite (DL6-D2); (f) trachyte (DL7B-D10); (g) rhyolite porphyry (MA1); (h) rhyolite porphyry with 1029

higher magnification (MA1). 1030

Fig. 3. Analysis of Curie points using magnetic susceptibility versus temperature curves. 1031

Fig. 4. Stereoplots and examples of demagnetisation behaviour for studied dykes. In orthogonal plots, 1032

open (closed) symbols show magnetisation vector endpoints in the vertical (horizontal) plane; curves 1033

show changes in intensity during demagnetisation. Stereoplots show upwards (downwards) pointing 1034

palaeomagnetic directions with open (closed) symbols. (a) rhyolite; (b) dolerite; (c) trachytes. 1035

Fig. 5. Stereoplots of the site mean palaeomagnetic directions. (a) 10 dykes; (b) 8 dykes (D4 and D8 1036

are excluded. 1037

Fig. 6. Representative zircon grains, and fragments, extracted from the sample D5. Upper image 1038

(optical microscope) shows prismatic grains with sharp edges between crystal surfaces (black arrows). 1039

Most grains have abundant fractures but are crystalline with no signs of radiation damage. Lower 1040

image (back-scattered electron image) shows two grains with no internal zoning, overgrowth or 1041

internal older components (cores). Some of the fractures probably stem from the polishing. White 1042

arrows depict sharp edges between crystal surfaces. 1043

Fig. 7. U-Pb Concordia diagram for the Lakhna sample D5. Dark grey ellipse defines the Concordia 1044

age for fraction Z1 and Z2. Ellipses depict 2s error. 1045

Fig. 8. (a) Total alkalis vs. SiO2 diagram for the classification of the Lakhna dykes (Le Bas et al., 1046

1986); (b) the shoshonite diagram of Peccerillo and Taylor (1976). Filled and open circles represent 1047

the alkalic series (Group 1 in Tables 3,4) and the sub-alkalic series (Group 2 in Tables 3,4) 1048

respectively. Red symbols denote samples analysed by ICP-MS at ACME Labs in Canada, blue 1049

symbols were analysed by ICP-AES at the Indian Institute of Technology, Bombay. 1050

31

Fig. 9. REE-chondrite normalised patterns for (1) mafic dykes of Group 1; (2) mafic dykes of Group 1051

2; (3) andesitic dykes; (4) dacite to rhyolite dykes. Normalisation values are from Sun and 1052

McDonough (1989). The solid and dashed lines indicate Group 1 and Group 2, respectively. 1053

Fig. 10. Primitive mantle-normalised incompatible trace element spidergrams for the (1) mafic dykes 1054

of Group1; (2) mafic dykes of Group 2; (3) andesitic dykes; (4) dacite to rhyolite dykes. 1055

Normalisation values are from Sun and McDonough (1989). The solid and dashed lines indicate 1056

Group-1 and Group-2, respectively. 1057

Fig. 11. Nb/La, Th/La and La/Yb versus SiO2 and MgO. Filled and open circles represent the alkalic 1058

series (Group 1 in Tables 3, 4) and the sub-alkalic series (Group 2 in Tables 3, 4) respectively. 1059

Fig. 12. Palaeomagnetically permissive 1460 Ma reconstructions of India (I) juxtaposed to: (a) SE 1060

Laurentia (L); (b) SW Laurentia; (c) SW Siberia (S); (d) SW Baltica (B) - Sarmatia. Hereafter: circles 1061

– Baltican poles; triangles – Laurentian poles; squares – Siberian poles; diamonds – Indian poles. 1062

Insets show geological matches/mismatches for each reconstruction. TIB - Transscandinavian Igneous 1063

Belt; GO - Gothian Orogeny; TA - Telemarkian accretionary events; DPO - Hallandian-Danopolonian 1064

orogeny; SNO - Sveconorwegian orogeny. Kimberlites and lamproites are located after Chalapathi 1065

Rao et al. (2004), Kumar et al. (2007), Bogatikov et al. (2007). Laurentian and Indian palaeopoles 1066

rotated together with continents (Table 6). Euler rotation parameters for India – see figure caption 13. 1067

Fig. 13. Palaeomagnetic testing of: (a) the India-SE Laurentia fit (Fig. 12a) at ~1190 Ma and ~1080 1068

Ma (India is rotated to Laurentia about an Euler pole of 16.01°S, 7.90°W at 136.28° anticlockwise); 1069

(b) the India-SW Laurentia fit (Fig. 12b) at ~1190 Ma and ~1080 Ma (India is rotated to Laurentia 1070

about an Euler pole of 8.73°N, 20.68°W at 106.10° anticlockwise); (c) the India-SW Siberia fit (Fig. 1071

12c) at ~1190 Ma and ~1080 Ma (India is rotated to Siberia about an Euler pole of 28.63°N, 93.94°E 1072

at 129.84° clockwise); (d) the India-SW Baltica fit (Fig. 12d) at ~1120 Ma and ~1080 Ma (India is 1073

rotated to Baltica about an Euler pole of 30.67°N, 54.34°E at 184.93° clockwise).. 1074

Online appendixes 1075

Appendix A: Plots of major and selected trace elements against SiO2. Symbology as in Fig. 8. 1076

32

Appendix B: Na2O and K2O versus LOI and Zr. Filled and circles represent the alkalic series (Group1 1077

in Tables 3 and 4) and the sub-alkalic series (Group 2 in Tables 3 and 4) respectively. 1078

Appendix C: Standard data and average value of samples analysed in laboratory in IIT Bombay (JSY-1079

1, JG, JR-3, JG2 and JG1a) and in ACME Ltd (SO-18). 1080

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Table 1. Paleomagnetic directions of Lakhna dykes

# Location

n/N D I K α95 Plat Plong dp dm

N E

(°) (°)

(°) (°N) (°E) (°) (°)

D1 20°44.957' 82°38.951' 10/13 50.6 58.4 19.1 11.4 43.2 137.9 12.5 16.9 D2 20°45.086' 82°39.001' 4/4 96.0 61.6 43.4 14.1 9.7 130.4 16.8 21.8 D3 20°44.890' 82°38.937' 10/16 57.1 59.5 11.0 15.3 38.1 137.0 17.3 23.0 D4 20°43.981' 82°39.520' 6/11 338.5 67.1 21.2 14.9 56.3 57.4 20.5 24.7 D5 20°45.114' 82°39.853' 7/9 64.9 56.6 19.0 14.2 32.0 141.0 14.9 20.6 D6 20°45.534' 82°40.810' 5/5 42.2 55.1 48.6 11.1 50.3 141.4 11.2 15.8 D7 20°45.533' 82°40.341' 6/9 293.6 -67.0 31.7 12.1 1.6 119.1 16.6 20.0 D8 20°44.360' 82°36.596' 6/8 93.8 -67.6 24.2 13.9 17.9 40.7 19.4 23.2 D10 20°45.153' 82°38.924' 14/18 51.7 65.2 17.8 9.7 40.8 127.4 12.7 15.7 Tr1 20°43.840' 82°38.785' 11/12 19.7 54.7 38.8 7.4 67.2 127.7 7.4 10.5

All mean

10/79 48.5 68.7 14.4 13.2 41.3 120.5 18.9 22.3

Mean without D4,D8

8/60 58.7 62.5 30.7 10.2 36.6 132.8 12.4 15.9

N/n=number of samples/specimens; D, I=sample mean declination, inclination; k =best estimate of the precision parameter of Fisher (1953);

95= the semi-angle of the 95% cone of confidence; Plat, Plong = latitude, longitude of the palaeopole; dp ,dm =the semi-axes of the cone of confidence about the pole at the 95% probability level.

Table 2. U-Pb TIMS data

Analysis no. U/ Pbc/ 206Pb/ 207Pb/ ± 2s 206Pb/ ± 2s

207Pb/ 206Pb/ 207Pb/ ± 2s Concord- (number of grains) Th Pbtot1)

204Pb 235U

% err 238U

% err

235U 238U 206Pb ance

raw2) [corr]3) [age, Ma]

Z1 (3 grains) 1.2 0.027 1892.9 3.2329 0.32 0.25509 0.27

1465.1 1464.7 1465.7 3.3 0.999

Z2 (3 grains) 1.3 0.026 1964.7 3.2427 0.38 0.25602 0.31 1467.4 1469.4 1464.6 4.1 1.003 1) Pbc = common Pb; Pbtot = total Pb (radiogenic + blank + initial).

2) measured ratio, corrected for fractionation and spike. 3) isotopic ratios corrected for fractionation (0.1% per amu for Pb), spike contribution, blank (1 pg Pb and 0.1 pg U), and initial common

Pb. Initial common Pb corrected with isotopic compositions from the model of Stacey and Kramers (1975) at the age of the sample.

Table 3. Major and trace elements (Canada)

Sample Sample

1 Sample

2 Sample

3 Sample

4 Sample

5 Sample

6 Sample

7 Sample

8 Sample

9 Sample

10 Dyke # (palaeomag) D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 Group 1.00 2.00 1.00 1.00 2.00 1.00 1.00 2.00 2.00 1.00 Major elements (%)

SiO2 49.2 48.4 53.0 46.2 75.0 64.4 44.2 49.4 52.7 58.8 TiO2 2.72 2.18 2.06 2.96 0.250 0.790 3.83 1.38 1.49 1.05 Al2O3 14.4 13.0 14.8 14.3 12.1 14.8 13.8 13.6 14.4 15.6 Fe2O3 total 13.0 15.2 11.7 14.2 2.36 6.48 16.3 16.0 15.3 7.37 MgO 2.92 6.26 2.14 5.50 0.800 1.50 4.51 5.20 2.61 3.72 CaO 5.87 9.58 4.93 8.68 0.380 0.850 7.81 9.11 7.46 0.910 Na2O 3.06 2.17 3.24 2.21 2.56 3.79 2.42 2.31 3.00 0.840 K2O 4.19 0.860 4.74 2.19 4.60 4.73 2.77 0.620 0.610 8.19 P2O5 1.23 0.260 0.950 0.930 0.0300 0.230 1.34 0.170 0.290 0.320 MnO 0.230 0.230 0.210 0.190 <0.01 0.0900 0.220 0.210 0.190 0.0600 Cr2O3 <0.002 0.0190 <0.002 0.0130 <0.002 <0.002 <0.002 0.0110 0.00300 <0.002 LOI 2.40 1.50 1.60 2.00 1.40 2.00 2.20 1.60 1.70 2.80 Sum 99.3 99.6 99.4 99.4 99.6 99.7 99.4 99.7 99.8 99.7 Trace elements (ppm)

Be 1.00 <1 <1 <1 2.00 3.00 2.00 <1 <1 <1 Sc 23.0 47.0 21.0 29.0 <1 7.00 26.0 39.0 28.0 19.0 V 98.0 373 40.0 274 <8 20.0 242 361 161 <8 Co 53.2 57.3 24.4 52.9 32.6 24.0 53.4 63.5 52.9 9.10 Ni 7.00 29.6 3.70 37.8 2.60 6.20 15.2 24.4 10.7 2.10 Cu 13.9 64.0 8.40 51.1 0.900 11.1 20.4 178 83.7 1.40 Zn 94.0 72.0 83.0 65.0 44.0 118 96.0 48.0 77.0 65.0 Ga 19.8 19.2 19.5 17.3 27.7 30.7 19.1 18.6 19.9 22.6 As 0.900 0.900 <0.5 0.600 0.700 0.700 1.60 <0.5 <0.5 0.600 Se <0.5 <0.5 <0.5 <0.5 1.00 <0.5 <0.5 <0.5 <0.5 <0.5 Rb 71.4 35.7 84.3 95.6 154 167 71.0 25.9 19.7 213 Sr 606 282 593 780 14.4 80.2 796 141 163 41.4 Y 30.3 36.0 30.6 20.6 99.8 58.4 25.5 33.0 52.4 38.1 Zr 206 150 247 116 823 565 177 108 220 307 Nb 38.4 19.7 41.9 22.4 157 77.1 32.4 5.10 9.20 59.1 Mo 1.00 0.700 1.10 0.500 0.800 2.40 0.800 0.500 0.600 1.70 Ag <0.1 0.100 0.100 0.100 <0.1 0.200 0.100 <0.1 <0.1 <0.1 Cd <0.1 <0.1 <0.1 <0.1 <0.1 0.100 <0.1 0.100 0.100 <0.1 Sn 1.00 2.00 <1 <1 6.00 7.00 <1 1.00 2.00 2.00 Sb <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Cs 0.800 0.400 1.30 1.30 0.600 0.200 0.500 0.100 0.200 0.400 Ba 3793 383 3583 2287 127 520 2314 199 293 1029 La 55.3 18.9 59.0 32.2 254 151 44.8 8.90 17.0 88.7 Ce 123 43.9 129 72.4 506 315 103 22.3 43.8 190 Pr 14.2 5.34 15.0 8.38 50.3 30.9 11.8 2.83 5.39 19.8 Nd 59.4 23.4 63.4 39.0 184 110 50.9 13.8 26.2 74.5 Sm 10.6 5.36 10.4 6.63 28.4 16.5 9.28 3.92 6.35 11.7 Eu 5.41 1.77 5.59 3.29 0.720 1.45 4.33 1.27 2.05 3.36 Gd 8.97 6.21 8.69 5.55 22.3 11.7 7.89 4.81 7.98 8.62 Tb 1.22 1.08 1.25 0.800 3.48 1.93 1.11 0.890 1.46 1.34 Dy 6.23 6.53 6.05 4.11 18.7 9.84 5.43 5.29 8.67 7.07 Ho 1.00 1.21 1.03 0.700 3.36 1.84 0.910 1.15 1.84 1.29 Er 2.67 3.51 2.89 1.75 9.16 5.34 2.18 3.51 5.43 3.45 Tm 0.390 0.570 0.430 0.290 1.44 0.910 0.370 0.540 0.890 0.580 Yb 2.25 3.35 2.41 1.48 8.36 5.01 1.86 3.33 5.34 3.53 Lu 0.350 0.550 0.390 0.230 1.26 0.780 0.310 0.540 0.830 0.560 Hf 4.60 4.50 6.10 3.00 23.6 13.7 4.80 2.50 5.70 7.40

Ta 2.40 1.20 2.50 1.30 9.10 4.70 2.40 0.400 0.800 3.60 W 79.7 86.3 84.4 53.2 357 167 68.2 112 172 58.4 Au 3.80 3.00 4.50 1.80 1.90 2.00 1.00 3.50 2.50 1.60 Hg <0.01 <0.01 0.0200 <0.01 <0.01 0.0200 <0.01 0.0200 0.0200 <0.01 Tl <0.1 <0.1 <0.1 0.200 0.200 0.200 <0.1 <0.1 <0.1 <0.1 Pb 1.90 1.30 2.40 1.50 4.30 23.4 2.40 0.800 1.50 2.40 Bi <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Th 3.70 1.60 4.00 2.50 39.8 21.1 3.90 1.30 3.00 7.50 U 0.700 0.500 0.700 0.500 5.50 3.30 0.700 0.400 0.800 1.80

Table 4. Major and trace elements (India)

Sample: MM6 MM4 MM8 MA1 PP3A GU1 PP5 KU3 KU4 PP2 LK2

B SL2 E2A E2D DL6 DL7B FP6 FPA FP2 BO3 LK-3A D1

Dyke # (palaeomag) G1 G1 D5 D5 Tr1 Tr1 D4 D5 D5 D2 D10 D5 D5 D5 D4 D4

Group 1.00 1.00 1.00 2.00 2.00 2.00 2.00 1.00 1.00 2.00 1.00 1.00 2.00 2.00 2.00 1.00 2.00 2.00 2.00 2.00 2.00 2.00

SiO2 52.1 52.2 70.5 68.5 48.4 73.3 74.4 59.4 61.4 48.9 47.3 46.0 49.1 62.2 49.1 56.6 74.0 73.0 76.7 48.9 43.3 51.3

TiO2 0.960 0.670 0.460 0.500 1.54 0.290 0.265 1.50 1.54 1.45 3.06 2.80 1.56 0.757 2.18 1.36 0.249 0.337 0.258 2.10 3.57 3.37

Al2O3 17.8 18.0 14.6 14.4 13.9 13.1 12.0 16.7 16.1 14.2 15.1 15.4 15.2 16.1 13.3 15.7 12.4 12.9 12.5 13.1 15.3 13.7

Fe2O3 total 10.0 9.74 5.05 5.50 14.6 3.68 3.54 6.25 6.24 14.0 14.9 14.1 12.9 6.93 15.5 11.1 4.06 4.74 2.81 14.7 15.8 13.4

MgO 0.240 0.240 0.860 1.10 6.13 1.28 0.953 3.52 3.34 6.17 5.43 5.24 6.27 3.51 5.84 3.75 0.686 0.534 0.794 6.06 6.13 5.24

CaO 2.90 3.01 1.18 1.37 9.36 0.120 0.470 0.508 0.470 10.9 7.47 9.40 9.93 1.71 9.83 0.452 0.404 0.997 0.430 9.92 10.0 9.66

Na2O 7.43 8.08 2.81 2.59 2.07 1.25 2.29 0.495 0.546 1.90 2.33 2.48 1.69 4.05 2.09 1.07 1.58 2.09 2.23 2.02 2.18 2.15

K2O 5.58 5.24 5.60 5.62 0.847 6.90 5.89 8.30 9.16 0.674 2.01 1.59 0.96

9 3.67 0.71

0 7.56 6.10 5.04 4.81 0.24

1 2.22 0.63

0

P2O5 0.050

0 0.030

0 0.070

0 0.090

0 0.086

0 0.0090

0 0.010

0 0.302 0.298 0.073

0 0.94

8 0.77

6 0.17

2 0.052

0 0.27

8 0.240 0.0010

0 0.0250 0.0010

0 0.23

9 1.10 0.29

0

MnO 0.350 0.350 0.060

0 0.070

0 0.202 0.0140 0.021

0 0.026

0 0.022

0 0.229 0.19

9 0.18

8 0.21

1 0.041

0 0.24

7 0.082

0 0.0250 0.0430 0.0100 0.22

7 0.22

9 0.22

0

LOI 2.04 1.99 1.14 0.014

0 1.84 1.09 1.10 3.23 1.73 1.88 1.77 2.44 2.80 1.74 1.16 2.51 0.720 0.0090

0 0.0073

0 2.78 2.06 2.02

Total 99.5 99.5 102 99.7 99.0 101 101 100 101 100 100 100 101 101 100 100 100 99.7 101 100 102 102

Trace element (ppm)

Sc 0 0.200 0.300 1.30 9.20 0.200 0 1.10 18.5 11.9 4.85 1.70 9.80 0.200 10.6 7.20 5.40 0 0.400 11.1 9.50 11.0

V 30.0 16.0 12.0 0 196 5.00 0 44.0 58.0 148 271 201 234 17.0 200 51.0 6.00 8.00 6.00 263 208 246

Cr 174 156 420 164 260 494 332 147 156 208 177 255 262 156 262 166 510 498 553 221 147 275

Co 6.00 11.0 3.00 4.00 46.0 1.00 1.00 9.00 14.0 45.0 43.0 46.0 41.0 22.0 45.0 8.00 10.0 1.00 1.00 42.0 42.0 43.0

Ni 12.0 15.0 19.0 21.0 76.0 21.0 22.0 16.0 17.0 85.0 46.0 101 40.0 18.0 43.0 16.0 21.0 21.0 20.0 46.0 42.0 44.0

Rb 134 114 162 159 46.0 213 184 160 181 41.0 70.0 56.0 41.0 202 39.0 159 212 203 187 33.0 49.0 44.0

Sr 2365 2232 54.0 80.0 385 15.0 15.0 59.0 61.0 151 593 674 196 54.0 189 46.0 14.0 20.0 10.0 170 749 223

Y 82.1 86.9 66.8 71.9 28.7 96.1 97.2 36.9 38.7 26.8 21.3 23.2 27.1 230 40.6 31.7 89.0 100 85.4 37.5 23.1 43.1

Zr 1135 1001 607 612 115 745 734 276 291 74.0 114 108 120 1373 153 282 403 459 382 143 40.0 117

Nb 296 235 74.6 124 20.8 148 118 44.4 50.8 20.6 26.1 30.8 7.60 138 25.2 42.6 133 148 142 21.8 27.8 41.6

Cs 13.1 11.5 9.80 8.80 7.50 8.90 12.0 10.2 6.60 10.6 4.30 2.00 4.20 14.0 9.30 5.30 6.70 8.50 11.2 7.80 11.5 9.00

Ba 385 369 579 567 524 305 119 1026 1024 158 2028 1196 224 129 213 706 163 91.0 118 120 1963 282

La 202 210 142 158 8.05 191 178 48.1 45.7 5.30 28.7 25.2 14.4 462 16.6 37.2 190 214 220 16.1 16.2 15.8

Ce 422 419 267 296 15.8 376 334 103 110 12.4 58.2 53.6 24.7 904 37.1 78.5 359 404 383 36.5 37.5 33.5

Pr 33.9 34.7 21.4 21.4 0.900 28.9 26.5 8.90 9.70 1.00 4.70 4.50 2.50 71.3 2.70 6.60 26.9 29.7 31.0 3.50 5.30 3.53

Nd 160 164 99.5 104 7.90 133 122 47.1 51.6 7.70 30.4 26.2 15.5 331 19.0 36.4 127 138 146 19.6 22.5 19.7

Sm 33.8 33.4 19.9 20.7 2.70 28.2 25.5 10.1 11.1 2.50 6.90 6.10 4.30 67.2 5.50 8.20 26.7 28.8 28.2 5.60 5.50 5.32

Eu 8.80 8.30 1.40 1.30 0.800 0.700 0.600 2.80 2.80 0.800 2.80 2.40 1.10 1.70 1.50 1.90 0.600 0.700 0.700 1.50 2.10 1.25

Gd 21.2 20.9 12.7 13.6 3.10 18.3 16.9 7.00 7.50 3.10 5.00 4.80 4.00 41.7 5.60 6.00 16.8 19.4 18.3 5.50 3.00 3.85

Tb 2.40 2.30 1.70 1.50 0.600 2.50 2.30 0.900 1.00 0.600 0.70

0 0.60

0 0.70

0 5.00 0.80

0 0.800 2.20 2.40 2.30 0.90

0 1.80 2.06

Dy 15.1 14.9 10.3 11.0 3.60 15.4 14.1 5.80 6.30 3.60 3.50 3.40 4.00 34.1 5.80 5.10 13.7 15.5 13.3 5.60 2.40 4.43

Ho 2.70 2.70 2.10 2.20 0.700 3.10 2.90 1.10 1.20 0.800 0.70

0 0.60

0 0.80

0 7.00 1.20 1.00 2.80 3.10 2.80 1.20 0.30

0 0.81

0

Er 6.10 6.50 5.40 5.70 2.30 8.50 7.60 2.80 3.40 2.40 1.70 1.60 2.30 17.9 3.40 2.60 7.50 7.70 7.10 3.40 1.50 3.26

Yb 4.50 4.70 4.80 5.10 2.20 7.10 6.70 2.50 3.00 2.20 1.30 1.30 2.10 16.5 3.10 2.50 6.40 7.10 5.80 3.10 1.30 2.87

Lu 0.600 0.700 0.700 0.800 0.400 1.10 1.00 0.400 0.500 0.300 0.20

0 0.20

0 0.30

0 2.51 0.50

0 0.400 1.00 1.10 0.900 0.50

0 1.70 2.03

Hf 50.0 45.0 15.9 15.9 6.40 19.4 19.5 7.20 7.10 2.40 4.80 3.10 3.40 69.4 8.70 7.40 15.0 19.5 16.5 4.20 1.10 3.70

Th 26.8 25.9 28.8 24.9 10.4 36.9 31.0 11.0 21.7 5.20 9.30 0.80

0 29.0 82.1 9.40 12.8 27.4 38.0 28.4 6.90 4.20 7.50

U 3.80 5.10 2.50 1.90 4.70 4.00 4.50 4.70 3.60 6.10 6.30 6.60 6.90 2.80 2.90 6.40 4.30 2.50 3.40 5.10 5.90 2.10

Table 5. Selected 1470-1000 Ma palaeomagnetic poles from Baltica, Laurentia, Siberia and India. ------------------------------------------------------------------------------------------------------------------------------------------------

Rockname Age Plat Plong A95 Reference

(Ma) (N) (E) ()

------------------------------------------------------------------------------------------------------------------------------------------------ Baltica

1a Mean for Baltica 1480-1450 17 178.0 11.0 Lubnina et al. (2010) 2b Mean for Baltica ~1265 4 158 4 Pesonen et al. (2003) 3 Salla Dyke VGP 1122±7 71 113 8 Salminen et al. (2009) 4c Bamble Intrusions 1100-1040 3 217 15 in Meert and Torsvik (2003) 5 Laanila Dolerite 1045±50 -2 212 15 Mertanen et al. (1996)

Laurentia

6d Mean for Laurentia 1480-1450 -4.4 214.2 16.0 Pisarevsky and Bylund (2010) 7 MacKenzie dykes 1267+7/-3 4 190 5 Buchan and Halls (1990), LeCheminant and Heaman (1989) 8 Hviddal Dyke, 1184±5 33 215 10 Piper (1977); Upton et al. (2003) Greenland 9 Narssaq Gabbro, 1184±5 32 221 10 Piper (1977); Upton et al. (2003) Greenland 10 Giant Gabbro Dykes, 1163±2 42 226 9 Piper (1977); Buchan et al. (2001) Greenland 11 South Qoroq Intr., 1165-1160 42 216 13 Piper (1992) Greenland 12 Osler Volc. 1105±2 43 195 6 Halls (1974); Davis and Green (1997) 13e Chengwatana Volc. 1095±2 31 186 8 Kean et al. (1997); Zartman et al. (1997) 14 Portage Lake Volc. 1095±3 27 178 5 Hnat et al. (2006); Davis and Paces (1990) 15 Cardenas Basalts 1091±5 32 185 8 Weil et al. (2003) 16 Lake Shore Traps 1087±2 22 181 5 Diehl and Haig (1994); Davis and Paces (1990) 17 Freda Sandstone 1050±30 2 179 4 Henry et al.(1977); Wingate et al. (2002) 18 Nonesuch Shale 1050±30 8 178 4 Henry et al.(1977); Wingate et al. (2002) 19 Chequamegon Sandst. 1050-990 -12 178 5 McCabe and Van der Voo (1983)

20 Jacobsville Sandstone 1050-990 -10 184 4 Roy and Robertson (1978) 21 Haliburton Intr. 1030-1000 -33 142 6 Warnock et al. (2000)

Siberia 22 Kyutingde, Sololi 1473±24 33.6 253.1 10.4 Wingate et al. (2009) intrusions, Siberia 23 Malgina Formation 1043±14 22 226 7 Gallet et al. (2000); Ovchinnikova et al. (2001) 24 Kumakha Formation 1040-1030 -14 201 7 Pavlov et al. (2000) 25 Milkon Formation ~1025 -6 196 4 Pavlov et al. (2000) 26 Nelkan Formation 1025-1015 -14 219 6 Pavlov et al. (2000) 27 Ignikan Formation 1015-1005 -16 201 4 Pavlov et al. (2000)

India 28 Lakhna Dykes, India 1465±3 36.6 132.8 14.0 This study 29 Harohalli alk. Dykes 1192±10 25 78 15 Pradhan et al. (2006) 30 Mahoba Dykes 1113±7 39 230 15 Pradhan et al. (2011) 31 Majhgawan Kim. VGP 1074±14 37 213 12 Gregory et al. (2006) 32 Anantapur Dykes 1027±13 9 213 11 Pradhan et al. (2010) ------------------------------------------------------------------------------------------------------------------------------------------------ a Averaged from: Lubnina (2009), Bylund (1985), Salminen and Pesonen (2007), Lubnina et al. (2010). b Averaged from: Neuvonen, 1965, 1966; Neuvonen and Grundström, 1969. c Averaged from: Stearn and Piper, 1984. d Averaged from: Meert and Stuckey (2002), Emslie et al. (1976), Irving et al. (1977). e Without regional tilt correction. VGP=Virtual Geomagnetic Pole

Table 6. Euler rotation parameters for Laurentia, Baltica and Siberia at 1460 – 1080 Ma (reconstructions in Figs. 11-15)

_____________________________________________________________________________ Craton Age Pole Angle (Ma) Lat(°) Lon(°) (°) _____________________________________________________________________________ Laurentia to absolute framework 1460 -48.68 48.60 166.26

1770 10.77 -17.29 -76.77 1750 14.27 -14.48 -71.78 1460 8.65 136.16 88.08 1265 21.42 122.39 89.97 Baltica to Laurentia 1460-1270 44.99 7.45 44.93 1120 -18.06 -126.33 -176.75 1080 50.07 -83.97 -45.93 Greenland to Laurentia 1460-1080 67.50 241.52 -14.00 Siberia to Laurentia 1460-1080 66.60 139.30 134.80 __________________________________________________________________